Relation
Middle English: from Old French, or from Latin relatio(n- ), from referre ‘bring back’ (see relate).
wiktionary
From Middle English relacion, relacioun, from Anglo-Norman relacioun and Old French relacion (whence French relation), from Latin relātiō, noun of process form from perfect passive participle relātus(“related”), from verb referō(“I refer, I relate”), from prefix re-(“again”) + ferō(“I bear, I carry”).
Morphologically relate + -ion
etymonline
relation (n.)
c. 1300, relacioun, "relationship, connection, correspondence;" late 14c. as "act of telling or relating in words," from Anglo-French relacioun, Old French relacion "report, connection" (14c.) and directly from Latin relationem (nominative relatio) "a bringing back, restoring; a report, proposition," from relatus (see relate).
The meaning "person related by blood or marriage" is attested from c. 1500. The phrase no relation "not in the same family," used in differentiating persons with the same surname, is attested by 1930.
